Think about all those punts on fourth-and-1, fourth-and-2, fourth-and-3. The average NFL offensive play gains about five yards. Yet game in, game out, coaches boom the punt away on short yardage, handing the most precious article in football -- possession of the ball -- to the other side. Nearly three-quarters of fourth-and-1 attempts succeed, while around one-third of possessions result in scores. Think about those fractions. Go for it four times on fourth-and-1 -- odds are you will keep the ball three times, and three kept possessions each with a one-third chance of a score results in your team scoring once more than it otherwise would have. Punt the ball on all four fourth-and-1s, and you've given the opponents three additional possessions. (It would have gotten one possession anyway when you missed one of your fourth-and-1s.) Those three extra possessions, divided by the one-third chance to score, give the opponent an extra score.
Someday there will be a coach who doesn't punt.